.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" Copyright (c) 2020      Google, LLC. All rights reserved.
.\" $COPYRIGHT$
.TH MPI_Info_get_nthkey 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_Info_get_nthkey\fP \- Returns the \fIn\fPth defined key in \fIinfo\fP.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Info_get_nthkey(MPI_Info \fIinfo\fP, int \fIn\fP, char \fI*key\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_INFO_GET_NTHKEY(\fIINFO, N, KEY, IERROR\fP)
	INTEGER		\fIINFO, N, IERROR\fP
	CHARACTER*(*)	\fIKEY\fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Info_get_nthkey(\fIinfo\fP, \fIn\fP, \fIkey\fP, \fIierror\fP)
	TYPE(MPI_Info), INTENT(IN) :: \fIinfo\fP
	INTEGER, INTENT(IN) :: \fIn\fP
	CHARACTER(LEN=*), INTENT(OUT) :: \fIkey\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
info
Info object (handle).
.ft R
.TP 1i
n
Key number (integer).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
key
Key (string).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
MPI_Info_get_nthkey returns the \fIn\fPth defined key in \fIinfo\fP. Keys are numbered 0\...\fIN\fP - 1 where \fIN\fP is the value returned by MPI_Info_get_nkeys. All keys between 0 and \fIN\fP - 1 are guaranteed to be defined. The number of a given key does not change as long as \fIinfo\fP is not modified with MPI_Info_set or MPI_Info_delete.

.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

.SH SEE ALSO
.ft r
MPI_Info_get
.br
MPI_Info_get_nkeys
.br
MPI_Info_get_valuelen
.br

